I. Field of the Invention
This invention relates generally to electrical connectors for connecting electrical assemblies or parts to a cable harness, and more particularly to a connector module assembly insertable into a receptacle of the electrical assembly incorporating active and passive circuit elements for effectively isolating the electrical assembly from electromagnetic interference (EMI), radio frequency interference (RFI), and electromagnetic transient pulses (EMP).
II. Discussion of the Prior Art
Present-day commercial and military aircraft incorporate complex electronic control systems incorporating numerous sensors and force transducers as well as the electronics necessary for processing the sensor signals and developing the requisite control signals for the transducers so that the aircraft can be flown in a controlled manner. Typically, the electronic assemblies involved will be housed in metallic shielding enclosures or boxes which are adapted to slide into equipment racks on the aircraft. Each of the electronic assemblies will typically incorporate a plug receptacle having a large number of terminal pins arranged in a grid configuration and which are appropriately wired to the electronic componentry within the shielded enclosure. Incorporated into the equipment rack assembly is a plug member which is adapted to mate with the plug receptacle on the shielded enclosure housing. The pins of the plug member are typically connected to conductors in a wiring harness leading off to the sensors and control transducers which may be spread throughout the aircraft.
A standard plug used throughout the aircraft industry is referred to as the ARINC 600 plug, which meets the ARINC specifications for air transport avionics equipment interfaces. That specification, among other things, defines the number of pins, their location, the pin spacing and the shell dimensions for the plug. Those desiring specific information relative to the plug are referred to the ARINC 600 specification itself.
The ARINC 600 plug is designed to mate with a plug receptacle attached to or formed into a wall of the shielding enclosure in which the electronics are contained. The ARINC 600 plug receptacle includes three sections with sections A and B each incorporating 150 male pins, each disposed in a grid array of rows and columns. Section C includes a smaller number of pins which, generally speaking, provide the power connections to the electronics module. The existing plug receptacle, designed to receive the plug member, includes a plurality of terminal pins having female sockets on one end and male wire wrap terminals or solder points on the other end. The pins are arranged in the same grid array, such that when the plug member is inserted into the plug receptacle, the male pins of the plug member engage the female sockets of the receptacle's terminal pins. The male portion of the receptacle's terminal pins are connected via wiring to electronic circuitry within the shielded enclosure.
The above-described prior art plug/receptacle combination has a number of inherent drawbacks. First of all, the prior art ARINC 600 connector design does not provide the necessary immunity of the electronic circuitry from the detrimental effects of EMI, RFI and EMP. Thus, for example, a lightning strike near the aircraft may induce a high voltage transient pulse (EMP) into the conductors of the wiring harness in the aircraft. Such transient pulses are oftentimes of an amplitude that can destroy CMOS circuitry forming a part of the electronic circuitry with which the ARINC 600 receptacle is interfaced to. Similarly, EMI and RFI radiation in proximity to the shielded enclosure may find a path into the interior of the shielded enclosure via the plug/receptacle assembly. These RFI/EMI and EMP sources may result in the electronic controls issuing erroneous data to the transducers with which it is associated, resulting in loss of control over the aircraft.
While filtering and transient suppression circuits have been devised for dealing with RFI/EMI and EMP radiation, physical space constraints may preclude inclusion of such circuitry within the shielded enclosure. A need, therefore, exists for a protection module insertable between and compatible with existing plugs and receptacles. A protection module which is sufficiently small to interface with existing plugs/receptacles yet which sufficiently protects electronics circuitry from EMI/RFI/EMP is desirable.
There is disclosed in the Paul et al. U.S. Pat. No. 4,789,360 and the Morse et al. U.S. Pat. No. 4,746,310, each assigned to Amphenol Corporation, electrical connectors having transient suppression discrete components incorporated therein. Moreover, the connector is designed such that the contact pins have mating forward and rearward end portions and a medial portion which includes a circuit protection element in the form of a packaged silicon diode or varistor. Because of the manner in which the connector pins are designed, it is possible to remove the forward end portion to allow repair or replacement of the circuit protection component. The physical size of the packaged silicon diode and its mode of attachment to the connector pin drastically limits the number of pins that can be arranged in the connector. Thus, the approach disclosed in those two Amphenol Corporation's patents is impractical in implementing a EMI/RFI/EMP connector receptacle compatible with the existing ARINC 600 plug having 2 sets of 150 pins/connector arrays.